Ordering Recommendation

Preferred genetic test for the detection of variants causing X-linked Alport syndrome.

Mnemonic

ALPORT FGA

Methodology

Polymerase Chain Reaction/ Sequencing/Multiplex Ligation-dependent Probe Amplification

Performed

Varies

Reported

28-35 days

New York DOH Approval Status

Specimens from New York clients will be sent out to a New York DOH approved laboratory, if possible.

Specimen Required

Patient Preparation
Collect

Lavender (EDTA), pink (K2EDTA), or yellow (ACD solution A or B).

Specimen Preparation

Transport 3 mL whole blood. (Min: 2 mL)

Storage/Transport Temperature

Refrigerated.

Unacceptable Conditions
Remarks
Stability

Ambient: 72 hours; Refrigerated: 1 week; Frozen: Unacceptable

Reference Interval

Interpretive Data

Background Information for: Alport Syndrome, X-linked (COL4A5) Sequencing and Deletion/Duplication
Characteristics:
Progressive renal and cochlear disease with 30-40 percent incidence of ocular involvement; 60 percent of males reach end-stage renal disease by age 30, and 85 percent have sensorineural deafness by age 40.
Incidence:
Approximately 1 in 50,000 live births.
Inheritance:
X-linked recessive; de novo mutations in 10-15 percent of affected males.
Penetrance:
Variable, depending on mutation and sex.
Cause:
Pathogenic type 4 collagen alpha chain 5 (COL4A5) mutations.
Clinical Sensitivity:
Greater than 80 percent for X-linked Alport syndrome in males or females.
Methodology:
Bidirectional sequencing of the entire COL4A5 coding region and intron-exon boundaries and multiplex ligation-dependent probe amplification (MLPA) to detect large COL4A5 coding region deletions and duplications.
Analytical Sensitivity & Specificity:
99 percent.
Limitations:
Diagnostic errors can occur due to rare sequence variations. Regulatory region mutations and deep intronic mutations will not be detected. Breakpoints of deletions/duplications will not be determined. Mutations in genes, other than COL4A5, are not evaluated. Deletions/duplications in exons 8, 25, 40, 42, and 43 of the COL4A5 gene will not be detected.

This test was developed and its performance characteristics determined by ARUP Laboratories. It has not been cleared or approved by the US Food and Drug Administration. This test was performed in a CLIA certified laboratory and is intended for clinical purposes.

Counseling and informed consent are recommended for genetic testing. Consent forms are available online.

Compliance Category

Laboratory Developed Test (LDT)

Note

Hotline History

N/A

CPT Codes

81407; 81408

Components

Component Test Code* Component Chart Name LOINC
2002399 ALPORT FGA Specimen 31208-2
2002401 Alport (COL4A5) Seq and Del/Dup Interp 53853-8
* Component test codes cannot be used to order tests. The information provided here is not sufficient for interface builds; for a complete test mix, please click the sidebar link to access the Interface Map.

Aliases

  • Alport syndrome molecular testing
  • X-linked Alport syndrome molecular testing
Alport Syndrome, X-linked (COL4A5) Sequencing and Deletion/Duplication (Temporary Referral as of 02/10/21)